Download Lesson 5a - protein shape

Aim: How is protein shape
determined?
What do enzymes, antibodies, hormones,
hemoglobin and membrane proteins have
in common?
Enzymes
Hemoglobin
All are proteins
with a specific
shape that
determines
their function.
Hormone
Antibodies
What determines a protein’s
Shape?
A protein’s shape is determined by its
sequence of amino acids.
What happens after translation
of the genetic code?
Proteins do not remain as single strands
of amino acids, rather the amino acids
chain gets folded into a specific shape.
This shape is determined by the ORDER
of the amino acids in the chain.
Protein Shape:
1) The DNA base sequence (order) determines
the sequence of amino acids.
2) The sequence (order) of amino acids in a
protein determine its shape.
3) The shape of a protein determines its activity.
Transcription & Translation:
The processes of
transcription and
translation, lead to
the final shape of a
protein. Therefore it
is the genetic code:
DNA base sequence
that ultimately
determine a protein’s
sequence of amino
acids.
A–T
U
C–G
G
C–G
G
Tryptophan
Mutations
Mutations (changes in the genetic code) that
can lead to changes in the amino acid
sequence and ultimately to the overall shape
of the protein. Why?
What causes mutations errors
in DNA replication?
• Chemicals
• UV Radiation
• X-Ray radiation
Mutated Proteins
It changes the amino acids sequence
which determines protein shape
How does a mutated protein
affect a cell?
•The mutated
protein may have a
different shape and
disrupt its normal
activity.
Types of Mutation
• Substitution
Original
DNA Strand
• Deletion
• Insertion
• Inversion
Copy the Normal DNA Strand:
DNA
CCT CAA GAT GCG
RNA
GGA GUU CUA CGC
AA Sequence
Gly – Val – Leu - Arg
Substitution and Deletion Mutations
• Substitution – One nitrogenous base is
substituted for another.
DNA
CCC CAA GAT GCG
mRNA
GGG GUU CUA CGC
• Deletion – One nitrogenous base is deleted
(removed).
DNA
CTC AAG ATG CG
mRNA
GAG UUC UAC GC
Insertion and Inversion Mutations
• Insertion – Extra nitrogenous bases are added to
the genetic code.
DNA
CCT CTA AGA TGC G
mRNA
GGA GAU UCU ACG C
• Inversion – The genetic code is inverted or
reversed.
DNA
CCT CAA TAG GCG
mRNA
GGA GUU AUC CGC
Sickle Cell Anemia
Point and Frame Shift Mutations
Point mutation
A change in ONE nitrogenous base, the overall number of bases stays the same
(Substitution or Inversion)
Frame shift mutation
A change in the number of overall nitrogenous bases in the genetic code
(Addition or Deletion)
What type of mutation is it?
Use the chart to complete your hand out